The long-term objective of this project is to determine how ethanol alters neuronal function. Actions of some neurotransmitters involves the membrane-bound enzyme adenylate cyclase, and the activity of this multicomponent system has previously been shown to be increased by ethanol. The specific aims of this project are: 1) to determine the site of action of ethanol on the adenylate cyclase system; 2) to determine whether chronic administration of ethanol alters the in vitro sensitivity of adenylate cyclase to ethanol, as well as the effect of chronic ethanol treatment on the lipid composition of the plasma membrane; 3) to determine the effect of specific changes in lipid composition of the plasma membrane on the in vitro sensitivity of adenylate cyclase to ethanol. The site of action of ethanol on the adenylate cyclase system will be determined by reconstitution of the purified regulatory subunit of adenylate cyclase into membranes from CYC-cells. The in vitro sensitivity of adenylate cyclase to ethanol will be determined after chronic exposure of both rats and PC12 cells to ethanol. Because tolerance to the effects of ethanol has been suggested to be caused by ethanol-induced changes in membrane lipid composition, changes in the lipid composition of synaptosomal plasma membranes from rat brain and plasma membranes from PC12 cells will also be determined after chronic ethanol administration. Relationship between changes in membrane lipid composition and the sensitivity of adenylate cyclase to ethanol will be further investigated by altering the membrane lipid composition of PC12 cells by incubating cells at different temperatures and by using various dietary supplements. Effect of specific changes in the lipid composition of the plasma membrane on the in vitro sensitivity of adenylate cyclase to ethanol will be determined by reconstituting the solubilized catalytic and regulatory subunits of adenylate cyclase into liposomes of known composition. Experiments in this project will increase our understanding of the mechanism of action and effects of ethanol. This knowledge should lead to the development of better treatment for alcoholism.